The i4xx cards have multiple universal digital i/o channels (referred to as "UIO"),
each of which can be independently programmed with software.
The i420,
i423 and
i430
have 4 UIO channels each; whereas the
i460
has 12 UIO channels.
For details, click on the links in the previous sentence.
For information on setting up digital & universal i/o channels, click
here.
Each UIO channel can be set up to do one of the following:

The Model 200 (not 230) instruNet PCI Controller boards have 10 digital
input/output channels, each of which can be used to output a continuous clock,
or a fixed number of pulses {1...2e9}. Set high time and
period of clock. If period > 10ms, then we generate clock with a 1ms timebase that drives two 0 to 32K
timers; otherwise, we use a 0.25us timebase. Periods must be >100us when fixing the # of pulses.
.